Nepean DamUnique for its Art deco style

Visit the Dam

Facilities

Children's playground

Drinking water

Barbecues

Parking

Portable toilet dump point

Toilets

Viewing areas

Hot Water

Disabled toilets

Picnic shelters

Nepean Dam was the last and smallest of the four dams constructed to collect water from the Illawarra Plateau south of Sydney. Today, you can walk across the dam wall, and soak up the Art Deco style of construction, which contrasts with the Egyptian influenced architecture of Avon and Cordeaux dams.

Lookout points

Dam wall

Walk across the dam wall for impressive views of the lake upstream and gorge downstream.

Viewing area above the dam wall

From the lower carpark near the dam wall, walk south along the former construction railway platform now housing log cabin-style picnic shelters to another viewing area of the lake.

No smoking within 10 metres of children's playgrounds and four metres of shelters, toilets and public buildings

Keep to vehicle speed limits and be aware of pedestrians

Recreation Areas at WaterNSW dams will be closed on ALL Total Fire Ban days.

The Nepean experience

Top 5 things to see and do

1. Walk across the dam wall

To fully appreciate your picturesque surroundings, take a walk across the dam wall. It's only 216 metres to the other end! Pause halfway and admire the views of the lake upstream. To better imagine how deep the lake is, cross to the other side of the wall and look down. You're 82 metres above the ground!

2. Step back in time

Be on the lookout for reminders of the dam's past as a favoured picnic spot in the 1930s and 1940s, when dams in the Upper Nepean would compete with each other for who had the most beautiful gardens. Enjoy the mixed plantings of European and native trees in a park-like picnic area along a terrace above the dam, and look out for a long line of Roman Cypress trees that follow the line of the spillway.

3. Soak up the views

Elevated paths and the dam wall provide impressive views of the lake in its natural bushland setting. Nepean Dam draws water from a 320 square kilometre catchment, the largest of the Upper Nepean dams. The Art Deco style of Nepean's large concrete structures contrasts with the Egyptian style of Avon and Cordeaux dams. Look out for the concrete lined side spillway, which looks like a smaller version of the massive auxiliary spillway at Warragamba Dam.

4. Check out the environmental flows

Variable environmental flows from Nepean Dam and the other Upper Nepean dams mimic natural river flows and help sustain the downstream river environment. Look downstream from the dam wall for the environmental flows that are released all day, every day for the health of the downstream river.

5. Relax with a picnic

Relax with family and friends in the landscaped grounds. Throw down a rug and picnic under a shady tree or use one of our tables or shelter sheds. Electric barbecues, drinking water and toilet facilities are located throughout the grounds. There's a children's playground at the top picnic ground. Nearer the dam wall, a row of small timber picnic shelters with a log cabin-style feel run along the remnant platform from the temporary railway built during the dam's construction.

Dam Summary

82

MetresHigh

Length: 216 metres

Size of lake:

3.3km2

Size of lake

67.73gltotal operating capacity

Catchment: 320 square kilometres

Facts & History

Located about 100 kilometres south of Sydney, Nepean Dam was the last and smallest of the four dams constructed to collect water from the Illawarra Plateau. Construction started in 1925 but stopped for two years during the Great Depression, before being completed in 1935.

Created by damming the Nepean River, Nepean Dam's main role today is to supply water to the nearby towns of Bargo, Thirlmere, Picton and The Oaks, as well as the Macarthur and Prospect water filtration plants.

It also receives water transferred from the Shoalhaven River and Kangaroo River when the Shoalhaven Scheme is in operation to top up our dams.

Together, the Nepean, Avon, Cataract and Cordeaux dams also provide an additional supply of water for Sydney, via Pheasants Nest Weir, Broughtons Pass Weir and the Upper Canal.

Why the dam was built

The Upper Nepean catchment south of Sydney is in one of the highest rainfall zones on the mid-NSW coast, and the area's rivers, located in narrow gorges, provide ideal dam sites.

As early as 1888, two weirs were built on the Cataract and Nepean rivers to capture this rainfall as part of the Upper Nepean Scheme to help meet Sydney's growing needs. Tunnels, canals and aqueducts - known as the Upper Canal - diverted the water 64 kilometres to Prospect Reservoir.

The scheme provided only temporary relief, and the 1901 - 1902 drought brought Sydney perilously close to a complete water famine. After two Royal Commissions, authorities agreed that a dam be built on Cataract River. The successive building of Cataract, Cordeaux, Avon and Nepean dams between 1907 and 1935 greatly increased the Upper Nepean Scheme's capacity.

How the dam was built

Work on Nepean Dam started in 1925, but was interrupted for a few years by the Depression before resuming in 1933. Materials were hauled on a standard gauge railway line from the main southern line near Bargo. The dam was finally completed in 1935.

Like all Upper Nepean dams, the wall was built using cyclopean masonry - sandstone blocks, quarried from the site, fitted into an irregular pattern and packed with sandstone concrete.

Most of the plant and equipment used for the construction of Avon Dam was dismantled and re-erected at the Nepean Dam site, including cableways and timber towers. A suspension bridge was constructed across the Nepean River which was later used at Warragamba Dam.

A township for workers was constructed of timber cleared from the Avon Dam catchment. A typical working man's accommodation consisted of a simple timber hut with a galvanised iron roof. Later, a barracks was constructed for single men. Married men had four and five-roomed cottages. A public school, recreation halls and medical facilities were also provided.

After several years of extremely low rainfall in the catchment, heavy rainfall in October 1938 saw the dam finally reach capacity and overflow via its spillway.

Later improvements

A tunnel linking Avon and Nepean dams, to enable the transfer of water between dams in either direction, was completed in 1973. In 2006 a deep water pumping station was built, allowing water to be transferred to Avon Dam even when the level of Nepean Dam is lower than Avon Dam.

To meet modern dam safety standards, Nepean Dam was strengthened in 1992 by post-tensioned anchors and a downstream rockfill embankment and further safeguarded by a concrete lined side spillway. The full supply level was also reduced by five metres as part of the upgrade.